When Alex Met Don Jr.

In a decidedly unhip slice of Manhattan, two scions of New York real-estate tycoons, average age 27&frac12;, plan to create a gleaming, 45-story condo-hotel, a rarity in city development.

Alex Sapir, 26, tumbled onto the New York City real-estate radar a year ago in March, taking the reins of his father Tamir’s real-estate empire as president of the Sapir Organization. Donald Trump Jr., 29, became executive vice president of development and acquisitions at the Trump Organization in 2004.

The project that they’re spearheading together, the Trump SoHo Hotel Condominium New York, is scheduled for a 2009 opening in Hudson Square—an area of Manhattan, if there ever was one, sorely in need of the touch of cool that only the moneyed young rich could provide. It’s in Soho, but not of Soho; instead, it’s a warehouse and loft district littered with empty storefronts and vacant office buildings.

“We want it to be the most iconic building in all of downtown and possibly in New York City,” Mr. Sapir told The Observer from his Mercedes, just returning to Manhattan from a vacation in Miami.

Mr. Trump, who has adapted over the last few years the workaholic habits of his father, said that Mr. Sapir’s a good listener. “He understands that we’re all young in this industry, and we need to be open to other people’s opinions,” Mr. Trump told The Observer. “We’re all working together to make sure it’s a true five-star downtown hotel.”

The 413-unit condo-hotel hybrid, one of only a handful in Manhattan, will offer 360-degree views of the city and beyond.

Assuming it gets built.

Controversy has dogged the Trump SoHo seemingly from its inception, leaving Mr. Sapir and Mr. Trump, whom one mutual intimate described as “socially friendly” but not necessarily friends, a stern task as they step further into the spotlight turned on by their fathers.

Developers announced the project last spring as a “transient hotel,” where well-heeled guests can buy one of the luxury rooms. In November, the developers obtained a building permit for the project in the low-rise manufacturing zone without public review, sparking criticism from city officials and preservationists.

Although transient hotels are legal in manufacturing districts, critics say the “guests” will be more like “residents,” living in the hotel year-round. Opponents of the tower, including Manhattan Borough President Scott Stringer, City Council Speaker Christine Quinn, U.S. Representative Jerrold Nadler and State Senator Tom Duane, have urged the city to enforce a stricter review of these projects, arguing that developers will be scouting manufacturing zones for sites to build towering condo-hotels masquerading as Trojan-horse transient hotels.

Although the city’s Planning Department is examining the complaints, changing the zoning laws will be a lengthy process, leaving Mr. Sapir and Mr. Trump space to muscle forward.

Right now, the Trump SoHo looks to be in limbo, with excavation at the site at Varick and Spring streets underway but construction still lacking. The city continues to review whether it’s more “condo” and less “hotel”—and, therefore, illegal.

Last week, after stepping out of a meeting with interior designer David Rockwell of the Rockwell Group, Mr. Sapir said that he’s working tirelessly on the building’s “timeless luxury,” poring over details until the early-morning hours in his Tribeca home.

“He has a very good feel for luxury,” Mr. Trump said of Mr. Sapir. (Bayrock, an investment firm, is also involved in the Trump SoHo’s development, along with the Sapir and Trump organizations.) “He understands it and has a vision of what he wants to achieve in the look, and ultimately what the clients are going to see and feel.”

While Mr. Sapir is passionate about woods and fabrics, Mr. Trump’s forte is the business side.

“He is able to bring practicality and a level head to what could seem to be a difficult task,” Mr. Sapir said. “I think it has shown, from working together, that the apple doesn’t fall far from the tree. His father has really helped shape his personality in business—and so has mine.”

Tamir (Tom) Sapir cultivated an image as an eccentric risk-taker: a Soviet immigrant cab driver who opened an electronics store, invested in Russian oil, then renovated white-elephant office buildings during the 1990’s recession to assemble an impressive portfolio. Early last year, he bought the Duke Semans mansion on Fifth Avenue for $40 million, the highest price then for a New York townhouse.

The Sapir Organization now owns more than seven million square feet of Manhattan office space, including 100 Church Street and 2 Broadway.

“When people say ‘Sapir,’ I want it to be synonymous with a great landlord, a great developer and a great family,” Alex Sapir said. “I want us to be the most recognized name in real estate in the world.”

That honor (and burden), of course, now falls on the Trumps.

Growing an empire for decades, one with roots in Queens, Donald Trump Sr. has been the omniscient face of New York City real estate—fiery, swooping bangs, grin drenched in self-confidence, name in lights in the heavens—for at least the last 20 years, eliciting the sorts of love-hate emotions normally reserved for politicians and pro athletes.

His oldest son brings a new, slicked-back charm to the dynasty.

At 13, he got his first job as a dock attendant at the Trump Castle marina in Atlantic City, making minimum wage plus tips. In interviews, he describes a continual, intrinsic fascination with his father’s business; he joined the Trump Organization in 2001. He told Sydney’s Sunday Telegraph Magazine in 2005 that he inherited his father’s “natural security, or ego.”

“I can be my own person and not have to live under his shadow,” he told the magazine. “I look up to him in many ways—I’d like to be more like him in business—but I’m such a different person, it’s hard to compare us.”

Mr. Sapir said that he talks to his father “26 times a day,” but only on the phone, since Tamir Sapir doesn’t have an e-mail address. The elder Sapir is wintering in Mexico, working on a new villa development in Acapulco.

When Alex was old enough, he helped his father on weekends at the family electronics store near Madison Square Park. “I wasn’t the whiz kid making sales at age 9,” he said. “But just being there watching my father, you know—I was spending time with a brilliant person, and hopefully that rubs off.”

Meanwhile, Alex got his business-management degree from Fordham University and studied law at Middlesex University in the United Kingdom. “I had some other ideas, but real estate is what worked,” he said.

He worked with his father on SDS Investments L.L.C., a private-equity real-estate fund with property in New York, Las Vegas and Miami, before graduating to become president of the Sapir Organization on March 8 last year.

“We’re usually in sync, but people disagree sometimes, and father and son disagree more than most people do,” the younger Mr. Sapir said. “But you suck it up—I respect his opinion more than anyone else’s.”

But it’s others’ opinions that will matter in the long run, with the eyes of many in a notoriously unforgiving business watching to see if Mr. Sapir and Mr. Trump can douse Hudson Square with a little condo-hotel glam.